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-rw-r--r--include/linux/perf_counter.h4
-rw-r--r--kernel/perf_counter.c83
2 files changed, 83 insertions, 4 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 6a384f04755..de70a10b5ec 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -178,8 +178,9 @@ struct perf_counter_attr {
mmap : 1, /* include mmap data */
comm : 1, /* include comm data */
freq : 1, /* use freq, not period */
+ inherit_stat : 1, /* per task counts */
- __reserved_1 : 53;
+ __reserved_1 : 52;
__u32 wakeup_events; /* wakeup every n events */
__u32 __reserved_2;
@@ -602,6 +603,7 @@ struct perf_counter_context {
int nr_counters;
int nr_active;
int is_active;
+ int nr_stat;
atomic_t refcount;
struct task_struct *task;
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index a72c20e9195..385ca51c6e6 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -236,6 +236,8 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
list_add_rcu(&counter->event_entry, &ctx->event_list);
ctx->nr_counters++;
+ if (counter->attr.inherit_stat)
+ ctx->nr_stat++;
}
/*
@@ -250,6 +252,8 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
if (list_empty(&counter->list_entry))
return;
ctx->nr_counters--;
+ if (counter->attr.inherit_stat)
+ ctx->nr_stat--;
list_del_init(&counter->list_entry);
list_del_rcu(&counter->event_entry);
@@ -1006,6 +1010,76 @@ static int context_equiv(struct perf_counter_context *ctx1,
&& !ctx1->pin_count && !ctx2->pin_count;
}
+static void __perf_counter_read(void *counter);
+
+static void __perf_counter_sync_stat(struct perf_counter *counter,
+ struct perf_counter *next_counter)
+{
+ u64 value;
+
+ if (!counter->attr.inherit_stat)
+ return;
+
+ /*
+ * Update the counter value, we cannot use perf_counter_read()
+ * because we're in the middle of a context switch and have IRQs
+ * disabled, which upsets smp_call_function_single(), however
+ * we know the counter must be on the current CPU, therefore we
+ * don't need to use it.
+ */
+ switch (counter->state) {
+ case PERF_COUNTER_STATE_ACTIVE:
+ __perf_counter_read(counter);
+ break;
+
+ case PERF_COUNTER_STATE_INACTIVE:
+ update_counter_times(counter);
+ break;
+
+ default:
+ break;
+ }
+
+ /*
+ * In order to keep per-task stats reliable we need to flip the counter
+ * values when we flip the contexts.
+ */
+ value = atomic64_read(&next_counter->count);
+ value = atomic64_xchg(&counter->count, value);
+ atomic64_set(&next_counter->count, value);
+
+ /*
+ * XXX also sync time_enabled and time_running ?
+ */
+}
+
+#define list_next_entry(pos, member) \
+ list_entry(pos->member.next, typeof(*pos), member)
+
+static void perf_counter_sync_stat(struct perf_counter_context *ctx,
+ struct perf_counter_context *next_ctx)
+{
+ struct perf_counter *counter, *next_counter;
+
+ if (!ctx->nr_stat)
+ return;
+
+ counter = list_first_entry(&ctx->event_list,
+ struct perf_counter, event_entry);
+
+ next_counter = list_first_entry(&next_ctx->event_list,
+ struct perf_counter, event_entry);
+
+ while (&counter->event_entry != &ctx->event_list &&
+ &next_counter->event_entry != &next_ctx->event_list) {
+
+ __perf_counter_sync_stat(counter, next_counter);
+
+ counter = list_next_entry(counter, event_entry);
+ next_counter = list_next_entry(counter, event_entry);
+ }
+}
+
/*
* Called from scheduler to remove the counters of the current task,
* with interrupts disabled.
@@ -1061,6 +1135,8 @@ void perf_counter_task_sched_out(struct task_struct *task,
ctx->task = next;
next_ctx->task = task;
do_switch = 0;
+
+ perf_counter_sync_stat(ctx, next_ctx);
}
spin_unlock(&next_ctx->lock);
spin_unlock(&ctx->lock);
@@ -1350,7 +1426,7 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu)
/*
* Cross CPU call to read the hardware counter
*/
-static void __read(void *info)
+static void __perf_counter_read(void *info)
{
struct perf_counter *counter = info;
struct perf_counter_context *ctx = counter->ctx;
@@ -1372,7 +1448,7 @@ static u64 perf_counter_read(struct perf_counter *counter)
*/
if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
smp_call_function_single(counter->oncpu,
- __read, counter, 1);
+ __perf_counter_read, counter, 1);
} else if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
update_counter_times(counter);
}
@@ -4050,7 +4126,8 @@ static void sync_child_counter(struct perf_counter *child_counter,
struct perf_counter *parent_counter = child_counter->parent;
u64 child_val;
- perf_counter_read_event(child_counter, child);
+ if (child_counter->attr.inherit_stat)
+ perf_counter_read_event(child_counter, child);
child_val = atomic64_read(&child_counter->count);